Organic electroluminescent display apparatus

ABSTRACT

An organic EL display apparatus ( 100 ) has a plurality of pixels including red pixels (R), green pixels (G) and blue pixels (B), the apparatus ( 100 ) including: a substrate ( 1 ); a plurality of organic EL elements ( 10 ) supported on the substrate, with one organic EL element provided in each pixel; a generally lattice-shaped first bank ( 21 ) defining the pixels, the first bank including a plurality of first portions ( 21 A) extending in a first direction and a plurality of second portions ( 21 B) extending in a second direction that crosses the first direction; and a plurality of second banks ( 22 ) provided on a top portion ( 21   t ) of the first bank, wherein the second banks are not formed at intersections (cr) between the first portions and the second portions of the first bank, and the second banks are more liquid repellent than the first bank.

TECHNICAL FIELD

The present invention relates to an organic EL display apparatus.

BACKGROUND ART

In recent years, organic EL (Electro Luminescence) display apparatuseshave started to be in practical use. An organic EL display apparatusincludes, for each pixel, at least one organic EL element (Organic LightEmitting Diode: OLED) and at least one TFT (Thin Film Transistor) forcontrolling the current flow supplied to the OLED. Each pixel is definedby a lattice-shaped structure formed from an insulating material (called“banks” or “partition walls”). Banks are provided on a flattening filmthat is formed so as to cover a circuit including TFTs (called a“driving circuit” or “backplane circuit”) (see, for example, PatentDocument No. 1).

An organic EL element of each pixel includes an anode that is connectedto a driving circuit, an organic EL layer provided on the anode, and acathode provided on the organic EL layer. An organic EL layer has alayered structure including a plurality of layers formed from an organicsemiconductor material. For example, the layered structure includes ahole injection layer, a hole transport layer, a light emitting layer, anelectron transport layer and an electron injection layer, in this orderstarting from the anode side. Organic EL layers of a red pixel, a greenpixel and a blue pixel include a light emitting layer that emits redlight, a light emitting layer that emits green light and a lightemitting layer that emits blue light, respectively.

The organic EL layer is formed on an anode located in a regionsurrounded by banks (a region to be a pixel) by using a vacuumdeposition method or a print method. That is, methods for forming anorganic EL layer are generally classified into “deposition-basedmethods” and “print-based methods”.

CITATION LIST Patent Literature

Patent Document No. 1: Japanese Laid-Open Patent Publication No.2016-85913

SUMMARY OF INVENTION Technical Problem

With the increasing definition of organic EL display apparatuses, theoccurrence of color mixture between red, green and blue is becomingpronounced. When color mixture occurs, the color purity of the displayedimage lowers, resulting in a so-called “dull” image, significantlylowering the display quality.

A cause for the occurrence of color mixture is that when forming lightemitting layers of different colors in corresponding pixels during amanufacturing process of an organic EL display apparatus, the lightemitting layer materials of adjacent pixels contaminate each other,thereby lowering the single-color color purity of red, green and blue.Such a problem can arise both with print-based methods and withdeposition-based methods.

The present invention has been made in view of the problem set forthabove, and it is an object of the present invention to provide anorganic EL display apparatus with which the occurrence of color mixtureis suppressed and which can display an image with a high color purity.

Solution to Problem

An organic EL display apparatus according to an embodiment of thepresent invention is an organic EL display apparatus having a pluralityof pixels including red pixels, green pixels and blue pixels, theapparatus including: a substrate; a plurality of organic EL elementssupported on the substrate, with one organic EL element provided in eachpixel; a generally lattice-shaped first bank defining the pixels, thefirst bank including a plurality of first portions extending in a firstdirection and a plurality of second portions extending in a seconddirection that crosses the first direction; and a plurality of secondbanks provided on a top portion of the first bank, wherein the pluralityof second banks are not formed at intersections between the firstportions and the second portions of the first bank, and the plurality ofsecond banks are more liquid repellent than the first bank.

In one embodiment, the first bank includes a side surface having atapered shape; and the plurality of second banks do not cover the sidesurface of the first bank.

In one embodiment, the plurality of second banks are colored.

In one embodiment, the first bank is formed from a non-fluorinenon-silicone resin.

In one embodiment, the first bank is formed from an acrylic resin, apolyamide or a polyimide with photosensitivity.

In one embodiment, the plurality of second banks are formed from anacrylic resin or a polyamide with negative photosensitivity.

In one embodiment, the plurality of second banks include a liquidrepellent material, or a liquid repellent treatment is performed on asurface thereof.

In one embodiment, the plurality of second banks include a second bankthat is located between two adjacent pixels of different colors.

In one embodiment, the pixels are arranged so as to include two adjacentpixels of the same color; and the plurality of second banks include asecond bank that is located between the two pixels of the same color.

In one embodiment, the pixels are arranged so as to include two adjacentpixels of the same color; and the plurality of second banks do notinclude any second bank that is located between the two pixels of thesame color.

In one embodiment, each of the organic EL elements includes a firstelectrode, an organic EL layer provided on the first electrode, and asecond electrode provided on the organic EL layer; and the organic ELlayer includes a plurality of print films layered together.

In one embodiment, each of the organic EL elements includes a firstelectrode, an organic EL layer provided on the first electrode, and asecond electrode provided on the organic EL layer; and the organic ELlayer includes a plurality of deposition films layered together.

Advantageous Effects of Invention

According to an embodiment of the present invention, it is possible toprovide an organic EL display apparatus with which the occurrence ofcolor mixture is suppressed and which can display an image with a highcolor purity.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a pixel array of an organic EL displayapparatus 100 according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing the organic ELdisplay apparatus 100, showing a cross section taken along line 2A-2A′of FIG. 1.

FIG. 3 is a perspective view schematically showing a first bank 21 andsecond banks 22 of the organic EL display apparatus 100.

FIG. 4 is a top view schematically showing the first bank 21 and thesecond banks 22 of the organic EL display apparatus 100.

FIG. 5 is a top view schematically showing the first bank 21 and thesecond banks 22 of the organic EL display apparatus 100.

FIGS. 6(a) and 6(b) are cross-sectional views schematically showing anLTPS-TFT 7 and an In—Ga—Zn—O-based TFT 8, respectively, to be used in adriving circuit 2 of the organic EL display apparatus 100.

FIG. 7 is a diagram showing another example pixel array (a pentilearray).

FIG. 8 is a top view schematically showing the first bank 21 and thesecond banks 22 of an organic EL display apparatus 100A of a pentilearray.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will now be described withreference to the drawings. Note that the present invention is notlimited to the following embodiments.

Referring to FIG. 1 and FIG. 2, an organic EL display apparatus 100 ofthe present embodiment will be described. FIG. 1 is a diagram showing apixel array of the organic EL display apparatus 100, and FIG. 2 is across-sectional view schematically showing the organic EL displayapparatus 100, showing a cross section taken along line 2A-2A′ of FIG.1.

As shown in FIG. 1, the organic EL display apparatus 100 includes aplurality of pixels, including red pixels R, green pixels G and bluepixels B. The pixels are arranged in a matrix pattern. One color displaypixel is formed by three pixels that display different colors from eachother (a red pixel R, a green pixel G and a blue pixel B). Note thatalthough an example where the red pixel R, the green pixel G and theblue pixel B have the same area is illustrated herein, the red pixel R,the green pixel G and the blue pixel B do not have need to have the samearea. Although a so-called striped array is illustrated herein, thepixel array is not limited to the striped array.

As shown in FIG. 2, the organic EL display apparatus 100 includes asubstrate 1, a driving circuit 2, a plurality of organic EL elements 10,and a thin film encapsulation (TFE) structure 30. The organic ELelements 10 are of a top-emission type, for example. A polarizer may bearranged on the TFE structure 30.

The substrate 1 is a polyimide film, for example. A polyimide film cansuitably be used as a flexible substrate 1. Note that a non-flexiblesubstrate (e.g., a glass substrate) may be used as the substrate 1.

The driving circuit (backplane circuit) 2 includes TFTs (not shownherein) formed on the substrate 1. The driving circuit 2 is covered by aflattening film 3.

The organic EL elements 10 are formed on the flattening film 3 andsupported by the substrate 1. The organic EL elements 10 are provided inrespective pixels. Each organic EL element 10 includes an anode (firstelectrode) 11, an organic EL layer 12 provided on the anode 11, and acathode (second electrode) 13 provided on the organic EL layer 12. Inthe illustrated example, the organic EL layer 12 includes a holeinjection layer 12 a, a hole transport layer 12 b, a light emittinglayer 12 c, an electron transport layer 12 d and an electron injectionlayer 12 e, in this order starting from the anode 11 side. Note that thelayered structure of the organic EL layer 12 is not limited to thelayered structure illustrated herein. Each of a plurality of organicsemiconductor layers of the organic EL layer 12 is herein a film formedby a print method (a print film). That is, the organic EL layer 12includes a plurality of print films layered together.

The TFE structure 30 has a layered configuration including inorganicbarrier layers and organic barrier layers alternating with each other.The specific configuration of the TFE structure 30 may be any of variousconfigurations known in the art.

The organic EL display apparatus 100 further includes a first bank 21defining a plurality of pixels, and a plurality of second banks 22provided on a top portion 21 t of the first bank 21. The first bank 21is formed on the flattening film 3. Although the end portion (edgeportion) of the anode 11 is located under the first bank 21 in theillustrated example, the end of the anode 11 may be spaced apart fromthe lower end of the first bank 21. The first bank 21 and the secondbanks 22 may be formed from a photosensitive resin material, as will bedescribed below.

Hereinafter, referring also to FIG. 3 and FIG. 4, the configuration ofthe first bank 21 and the second banks 22 will be described. FIG. 3 andFIG. 4 are a perspective view and a top view, respectively,schematically showing the first bank 21 and the second banks 22.

The first bank 21 is generally lattice-shaped, and includes a pluralityof portions (hereinafter referred to as “first portions”) 21A extendingin the row direction (the first direction), and a plurality of portions(hereinafter referred to as “second portions”) 21B extending in thecolumn direction (the second direction) that crosses (herein, generallyorthogonal to) the row direction. Pixels are individual areas that aresurrounded by the first bank 21. The first bank 21 includes the topsurface 21 t and a side surface 21 s having a tapered shape.

Each of the second banks 22 is a generally rectangular parallelepiped.As already described above, the second banks 22 are provided on the topportion (top surface) 21 t of the first bank 21. The second banks 22 arenot formed at the intersections cr between the first portions 21A andthe second portions 21B of the first bank 21. The second banks 22 do notcover the side surface 21 s of the first bank 21 and are not in contactwith the anode 11.

The second banks 22 are liquid repellent. In contrast, the first bank 21is not liquid repellent but is lyophilic. That is, the second banks 22are more liquid repellent than the first bank 21.

Herein, a bank, or the like, being “liquid repellent” means that thesurface of the bank, or the like, has a low wettability for a liquidmaterial (an ink for a print method). Specifically, it means that thebank surface at least has water repellency when a hydrophilic(water-dispersible) ink is used, and the bank surface at least has oilrepellency when a hydrophobic (organic solvent) ink is used. Also, itmeans that it has both water repellency and oil repellency when theorganic EL layer includes a layer formed from a hydrophilic ink and alayer formed from a hydrophobic ink.

On the other hand, a bank, or the like, being “lyophilic” means that thesurface thereof has a high wettability for a liquid material.Specifically, it means that the bank surface at least has hydrophilicitywhen a hydrophilic ink is used, and the bank surface at least hasoleophilicity when a hydrophobic ink is used. Also, it means that it hasboth hydrophilicity and oleophilicity when the organic EL layer includesa layer formed from a hydrophilic ink and a layer formed from ahydrophobic ink.

Moreover, the phrase “wettability being low” means that the contactangle of the bank surface for a liquid material is 90° or more, forexample, and the phrase “wettability being high” means that the contactangle of the bank surface for a liquid material is 40° or less, forexample. The contact angle is typically measured by using a sessile dropmethod.

As described above, with the organic EL display apparatus 100 of thepresent embodiment, a plurality of second banks 22 that are more liquidrepellent than the first bank 21 are provided on the first bank 21.Therefore, when the organic EL layer 12 is formed by a print methodduring the manufacturing process of the organic EL display apparatus100, it is possible to prevent an organic material (light emitting layermaterial) drop-fed into each pixel from leaking out to an adjacent pixel(to prevent a satellite droplet from landing on an adjacent pixel).Therefore, with the organic EL display apparatus 100, the occurrence ofcolor mixture is suppressed, and it is possible to display an image witha high color purity.

The second banks 22 are not formed at the intersections cr of the firstbank 21. A study by the present inventors revealed that when the secondbank 22 is formed also at the intersections cr of the first bank 21(i.e., a lattice-shaped second bank 22 is provided), underexposure orpatterning defect may occur on the photosensitive resin materialprovided on the intersections cr, and it is difficult to control theheight of the second bank 22 on the intersections. By not forming thesecond banks 22 at the intersections cr of the first bank 21 as in thepresent embodiment, it is possible to desirably control the height ofthe second banks 22.

Note that a conductive layer that forms the cathode 13 of each pixel maybecome discontinuous due to the step by the second bank 22, asillustrated in FIG. 2, but is continuous over the intersections cr wherethe second bank 22 is not formed.

Although a case where the organic EL layer 12 is formed by a print-basedmethod is illustrated herein, the embodiment of the present inventioncan realize the advantageous effects described above even when theorganic EL layer 12 is formed by a deposition-based method (i.e., whenthe organic EL layer 12 includes a plurality of deposition films layeredtogether). The provision of the second banks 22 increases the height ofthe structure (bank) that partitions between adjacent pixels from eachother, thereby making it possible to block an organic material thatcomes over from adjacent pixels due to shadowing. Thus, it is possibleto prevent color mixture.

In the present embodiment, the first bank 21 that is generallylattice-shaped and is not liquid repellent is provided under the secondbanks 22, and the second banks 22 do not cover the side surface 21 s ofthe first bank 21 (i.e., the side surface 21 s of the first bank 21 isexposed). Therefore, an organic material can be neatly applied acrossthe entire area within the pixels. That is, the pixels are defined bythe first bank 21.

The material of the first bank 21 may be a non-fluorine non-siliconeresin that does not turn liquid repellent, and specifically, an acrylicresin, a polyamide or a polyimide with photosensitivity may desirably beused. A photosensitive polyamide is disclosed in InternationalPublication WO2009/151012 pamphlet, for example.

An acrylic resin or a polyamide with negative photosensitivity maydesirably be used as the material of the second banks 22. With anegative photosensitive resin, portions that polymerize through lightirradiation increase the resistance against the developer, and portionsthat have been irradiated with light remain as a pattern after thedevelopment. Therefore, the degree of polymerization can be controlledby changing the amount of exposure, etc., thereby enhancing the abilityto control the pattern to be left remaining. Thus, since it is possibleto perform photolithography with a high precision by using the resinmaterial described above, it is possible to desirably form the secondbanks 22 on the first bank 21.

If the second banks 22 include a liquid repellent material or if aliquid repellent treatment is performed on the surface of the secondbanks 22, the second banks 22 can exhibit liquid repellency. The liquidrepellent material may be a fluorine-based liquid repellent material,for example. The liquid repellent treatment may be a plasma treatmentusing a fluorine-based gas such as carbon tetrafluoride (CF₄).

The second banks 22 may be colorless or colored. When the second banks22 are colored (e.g., black or dark brown), it is possible to controlthe light that comes diagonally out of the pixels, thereby improving theviewing angle characteristic.

There is no particular limitation on the height h1 of the first bank 21(see FIG. 3). The height h1 of the first bank 21 is 1 μm or more and 2μm or less, for example.

There is no particular limitation on the width w1 _(A) of the firstportion 21A and the width w1 _(B) of the second portion 21B of the firstbank 21 (see FIG. 4). The width w1 _(A) of the first portion 21A and thewidth w1 _(B) of the second portion 21B are set so that the firstportion 21A and the second portion 21B overlap with the anode 11 by 1 μmor more and 3 μm or less, for example.

While there is no particular limitation on the height h2 of the secondbanks 22 (see FIG. 3), it is preferably somewhat large and is preferably2 μm or more, for example, in order to prevent the occurrence of colormixture. Note however that when the height h2 of the second banks 22 isexcessive, it may lead to difficulties in the manufacture, and it ispreferably 5 μm or less, for example.

The width w2 of the second banks 22 (see FIG. 4) is set to be smallerthan the width of the first bank 21 (the width w1 _(A) of the firstportion 21A and the width w1 _(B) of the second portion 21B) by apredetermined amount. Specifically, the width w2 of the second banks 22is set in view of the alignment precision in the photolithographyprocess for forming the second banks 22 and so that the width of the topportion 21 t of the first bank 21 is smaller than the width of thebottom portion thereof (w1 _(A) and w1 _(B) described above), and is setto be smaller than the width of the first bank 21 (the width w1 _(A) ofthe first portion 21A and the width w1 _(B) of the second portion 21B by6 μm or more, for example.

The lengths 12 _(A) and 12 _(B) of the second banks 22 (see FIG. 4) arepreferably somewhat large in order to suppress the occurrence of colormixture. Specifically, the length 12 _(A) of the second bank 22 on thefirst portion 21A (a portion extending in the row direction) of thefirst bank 21 is preferably 80% or more of the length of the pixel alongthe row direction, and the length 12 _(B) of the second bank 22 on thesecond portion 21B (a portion extending in the column direction) of thefirst bank 21 is preferably 80% or more of the length of the pixel alongthe column direction.

Note that with the striped array illustrated in FIG. 1, etc., pixels ofdifferent colors are adjacent to each other along the row direction andpixels of the same color are adjacent to each other along the columndirection. Therefore, the second banks 22 on the first bank 21 includesecond banks 22 that are located between two pixels of different colors(the second banks 22 on the second portion 21B) and second banks 22 thatare located between two pixels of the same color (the second banks 22 onthe first portion 21A). Since color mixture does not occur betweenpixels of the same color, second banks 22 that are located between twopixels of the same color may be omitted as shown in FIG. 5.

Next, an example of a TFT used in the driving circuit 2 of the organicEL display apparatus 100 will be described.

A low-temperature polysilicon (abbreviated as “LTPS”) TFT or an oxideTFT (e.g., a quaternary (In—Ga—Zn—O-based) oxide TFT including In(indium), Ga (gallium), Zn (zinc) and O (oxygen)) having a high mobilitymay desirably be used in a high-definition, medium- or small-sizedorganic EL display apparatus. The structure and the manufacturing methodof an LTPS-TFT and an In—Ga—Zn—O-based TFT are well known in the art,and will be described only briefly below.

FIG. 6(a) is a cross-sectional view schematically showing an LTPS-TFT 7.The TFT 7 can be included in the driving circuit 2 of the organic ELdisplay apparatus 100. The TFT 7 is a top-gate TFT.

The TFT 7 is formed on a base coat layer 4 on the substrate (e.g., apolyimide film) 1. The base coat layer 4 is formed from an inorganicinsulating material.

The TFT 7 includes a polysilicon layer 7 a formed on the base coat layer4, a gate insulating layer 5 formed on the polysilicon layer 7 a, a gateelectrode 7 g formed on the gate insulating layer 5, an inter-layerinsulating layer 6 formed on the gate electrode 7 g, and a sourceelectrode 7 s and a drain electrode 7 d formed on the inter-layerinsulating layer 6. The source electrode 7 s and the drain electrode 7 dare connected to the source region and the drain region, respectively,of the polysilicon layer 7 a through contact holes formed in theinter-layer insulating layer 6 and the gate insulating layer 5.

The gate electrode 7 g is included in the same gate metal layer as thegate bus line, and the source electrode 7 s and the drain electrode 7 dare included in the same source metal layer as the source bus line.

FIG. 6(b) is a cross-sectional view schematically showing anIn—Ga—Zn—O-based TFT 8. The TFT 8 can be included in the driving circuit2 of the organic EL display apparatus 100. The TFT 8 is a bottom-gateTFT.

The TFT 8 is formed on the base coat layer 4 on the substrate (e.g., apolyimide film) 1. The TFT 8 includes a gate electrode 8 g formed on thebase coat layer 4, the gate insulating layer 5 formed on the gateelectrode 8 g, an oxide semiconductor layer 8 a formed on the gateinsulating layer 5, and a source electrode 8 s and a drain electrode 8 dconnected to the source region and the drain region, respectively, ofthe oxide semiconductor layer 8 a. The source electrode 8 s and thedrain electrode 8 d are covered by the inter-layer insulating layer 6.The gate electrode 8 g is included in the same gate metal layer as thegate bus line, and the source electrode 8 s and the drain electrode 8 dare included in the same source metal layer as the source bus line.

Next, a method for manufacturing the organic EL display apparatus 100will be described. Herein, an example where the driving circuit 2includes the LTPS-TFT 7 will be described. The organic EL displayapparatus 100 can be manufactured as follows, for example.

A polyimide film having a thickness of 10 μm or more and 20 μm or less,for example, is prepared as the substrate 1. The polyimide film isformed on a glass plate. The polyimide film may be a single layer, ormay have a two-layer configuration including an inorganic film (an SiO₂film, etc.) sandwiched between two polyimide layers.

A layered inorganic film (e.g., SiO₂ film/SiN_(x) film/SiO₂ film) isformed as the base coat layer 4 on the substrate 1.

An a-Si film having a thickness of 50 nm or more and 100 nm or less, forexample, is deposited by a plasma CVD method on the base coat layer 4.

The a-Si film is dehydrogenated (e.g., annealed at 450° C. for 180 min).

The a-Si film is polysiliconized by an excimer laser annealing (ELA)method.

The a-Si film is patterned by a photolithography process, therebyforming an active layer (a semiconductor island).

An SiO₂ film having a thickness of 100 nm, for example, is deposited bya plasma CVD method as the gate insulating layer 5 covering the activelayer.

The channel region of the active layer is doped (B⁺).

An Mo film having a thickness of 250 nm, for example, is deposited by asputtering method as a gate metal on the gate insulating layer 5, andthe gate metal is patterned by a photolithography process, therebyforming the gate electrode 7 g and the gate bus line.

The source region and the drain region of the active layer are doped(P⁺).

An activation anneal (e.g., an anneal at 450° C. for 45 min) isperformed. Thus, the polysilicon layer 7 a is obtained.

An SiN_(x) film or an SiO₂ film having a thickness of 100 nm or more and300 nm or less, for example, is deposited by a plasma CVD method as theinter-layer insulating layer 6 covering the gate electrode 7 g, etc.

Contact holes are formed in the gate insulating layer 5 and theinter-layer insulating layer 6 by wet etching and dry etching.

A layered film of Ti film/Al film/Ti film (thickness: 50 nm/500 nm/100nm, for example) is deposited by a sputtering method as a source metalon the inter-layer insulating layer 6, and the source metal is patternedby a photolithography process, thereby forming the source electrode 7 s,the drain electrode 7 d and the source bus line. Thus, the TFT 7 iscompleted.

A polyimide film or an acrylic resin film having a thickness of 2 μm,for example, is deposited by a slit coater, or the like, as theflattening film 3 so as to cover the TFT 7, etc.

A layered film of ITO film/Ag or APC film/ITO film (thickness: 5 nm/100nm/5 nm, for example) is deposited and patterned as the anode 11 on theflattening film 3.

The generally lattice-shaped first bank 21 is formed on the flatteningfilm 3. A photosensitive acrylic resin or a polyamide that is not liquidrepellent is used as the material of the first bank 21. Alternatively, apolyimide may be used. The height of the first bank 21 is 1 μm or moreand 2 μm or less, for example.

A plurality of second banks 22 are formed on the top portion 21 t of thefirst bank 21. The second banks 22 are not formed at the intersectionscr of the first bank 21. An acrylic resin or a polyamide with negativephotosensitivity is used as the material of the second banks 22. Thus,it is possible to performed a high-precision photolithography process. Afluorine-based liquid repellent material is added to the material of thesecond banks 22. Alternatively, a liquid repellent treatment (e.g., aplasma treatment using CF₄) may be performed on the surface of thesecond banks 22. The height of the second banks 22 is 2 μm or more and 5μm or less, for example.

Then, the organic EL layer 12 is formed by a print method or a vacuumdeposition method, and then the cathode 13 is formed. Thereafter, theTFE structure 30 is formed on the organic EL element 10.

Thus, the organic EL display apparatus 100 is obtained.

While a case where the pixel array is a striped array has beenillustrated in the description above, the embodiment of the presentinvention is not limited thereto. The pixel array may be a pentile arrayas shown in FIG. 7, for example. The pentile array illustrated in FIG. 7is referred to also as a diamond pentile array.

FIG. 8 shows a configuration of the first bank 21 and the second banks22 of the organic EL display apparatus 100A having a diamond pentilearray.

When the pixel array is a diamond pentile array, the directions in whichthe first portions 21A and the second portions 21B of the first bank 21extend are different by about 45° from those of a striped array, asshown in FIG. 8. Also with this configuration, by providing the secondbanks 22 that are more liquid repellent than the first bank 21 on thetop portion 21 t of the first bank 21, it is possible to realize similaradvantageous effects.

INDUSTRIAL APPLICABILITY

According to the embodiment of the present invention, the occurrence ofcolor mixture is suppressed, and it is possible to provide an organic ELdisplay apparatus which can display an image with a high color purity.The embodiment of the present invention can be desirably used inhigh-definition organic EL display apparatuses.

REFERENCE SIGNS LIST

-   -   1: Substrate, 2: Driving circuit, 3: Flattening film, 7:        LTPS-TFT, 8: In—Ga—Zn—O-based TFT, 10: Organic EL element, 11:        Anode, 12: Organic EL layer, 12 a: Hole injection layer, 12 b:        Hole transport layer, 12 c: Light emitting layer, 12 d: Electron        transport layer, 12 e: Electron injection layer, 13: Cathode,        21: First bank, 21A: First portion of first bank, 21B: Second        portion of second bank, 21 t: Top portion (top surface) of first        bank, 21 s: Side surface of first bank, 22: Second bank, 30: TFE        structure, 100: Organic EL display apparatus, R: Red pixel, G:        Green pixel, B: Blue pixel, cr: Intersection of first bank

The invention claimed is:
 1. An organic EL display apparatus having aplurality of pixels including red pixels, green pixels and blue pixels,the apparatus comprising: a substrate; a plurality of organic ELelements supported on the substrate, with one organic EL elementprovided in each pixel; a generally lattice-shaped first bank definingthe pixels, the first bank including a plurality of first portionsextending in a first direction and a plurality of second portionsextending in a second direction that crosses the first direction; and aplurality of second banks provided on a top portion of the first bank,wherein the plurality of second banks are not formed at intersectionsbetween the first portions and the second portions of the first bank,and the plurality of second banks are more liquid repellent than thefirst bank.
 2. The organic EL display apparatus of claim 1, wherein: thefirst bank includes a side surface having a tapered shape; and theplurality of second banks do not cover the side surface of the firstbank.
 3. The organic EL display apparatus of claim 1, wherein theplurality of second banks are colored.
 4. The organic EL displayapparatus of claim 1, wherein the first bank is formed from anon-fluorine non-silicone resin.
 5. The organic EL display apparatus ofclaim 4, wherein the first bank is formed from an acrylic resin, apolyamide or a polyimide with photosensitivity.
 6. The organic ELdisplay apparatus of claim 1, wherein the plurality of second banks areformed from an acrylic resin or a polyamide with negativephotosensitivity.
 7. The organic EL display apparatus of claim 1,wherein the plurality of second banks include a liquid repellentmaterial, or a liquid repellent treatment is performed on a surfacethereof.
 8. The organic EL display apparatus of claim 1, wherein theplurality of second banks include a second bank that is located betweentwo adjacent pixels of different colors.
 9. The organic EL displayapparatus of claim 8, wherein: the pixels are arranged so as to includetwo adjacent pixels of the same color; and the plurality of second banksinclude a second bank that is located between the two pixels of the samecolor.
 10. The organic EL display apparatus of claim 8, wherein: thepixels are arranged so as to include two adjacent pixels of the samecolor; and the plurality of second banks do not include any second bankthat is located between the two pixels of the same color.
 11. Theorganic EL display apparatus of claim 1, wherein: each of the organic ELelements includes a first electrode, an organic EL layer provided on thefirst electrode, and a second electrode provided on the organic ELlayer; and the organic EL layer includes a plurality of print filmslayered together.
 12. The organic EL display apparatus of claim 1,wherein: each of the organic EL elements includes a first electrode, anorganic EL layer provided on the first electrode, and a second electrodeprovided on the organic EL layer; and the organic EL layer includes aplurality of deposition films layered together.